AU2018243740B2

AU2018243740B2 - Fertilizers containing slow and fast release sources of boron

Info

Publication number: AU2018243740B2
Application number: AU2018243740A
Authority: AU
Inventors: Roslyn BAIRD; Rodrigo Coqui Da Silva; Jozefien DEGRYSE; Kyle Freeman; Thomas Fry; Michael Mclaughlin
Original assignee: Mosaic Co
Current assignee: Mosaic Co
Priority date: 2017-03-31
Filing date: 2018-03-30
Publication date: 2023-02-02
Anticipated expiration: 2038-03-30
Also published as: JP2020512967A; IL307808A; EP3601200A4; US12391625B2; AU2023202723A1; AU2018243740A1; MY202979A; MX2025012321A; CO2019012046A2; CL2019002782A1; RU2019134548A3; US10717682B2; JP6995877B2; IL269696B2; US20210347704A1; IL269696B1; US20180290940A1; MX2019011737A; NZ758797A; BR112019020530A2

Abstract

A granular fertilizer product having at least two sources of boron having different solubilities to tailor boron availability during the entire growing season of a plant, while reducing the risk of boron toxicity. A first source of boron can include a sodium-based or highly water soluble boron compound such as sodium tetraborate and/or boric acid, while a second source of boron can include a calcium-based boron compound such as colemanite (CaB

Description

FERTILIZERS CONTAINING SLOW AND FAST RELEASE SOURCES OF BORON RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Application No.

62/479,948 filed March 31, 2017, which is hereby incorporated herein in its entirety by

reference. The present application is related to U.S. Patent No. 9,266,784, which claims the

benefit of U.S. Provisional Application No. 61/514,952 filed August 4, 2011, both of which are

incorporated herein in their entirety by reference.

TECHNICAL FIELD

The invention relates generally to fertilizer compositions. More specifically, the invention

relates to incorporation of at least two different sources of boron into a macronutrient carrier

fertilizer as a means of providing plants more timely access to boron.

BACKGROUND

Essential plant nutrients can be divided into two groups, the macronutrients, both primary

and secondary, and micronutrients. Plants access primary nutrients including nitrogen,

phosphorus, and potassium from the soil and hence they make up the major part of fertilizers

used to supplement soils that are lacking in these nutrients.

According to the conventional fertilizer standards, the chemical makeup or analysis of

fertilizers is expressed in percentages (by weight) of the essential primary nutrients nitrogen,

phosphorus, and potassium. More specifically, when expressing the fertilizer formula, the first

value represents the percent of nitrogen expressed on the elemental basis as "total nitrogen" (N),

the second value represents the percent of phosphorus expressed on the oxide basis as "available

phosphoric acid" (P 2 0 5), and the third value represents the percent of potassium also expressed on the oxide basis as "available potassium oxide" (K 2 0), or otherwise known as the expression

(N-P 20 5-K 20).

Even though the phosphorus and potassium amounts are expressed in their oxide forms,

there technically is no P 2 0 5 or K 2 0 in fertilizers. Phosphorus exists most commonly as

monocalcium phosphate, but also occurs as other calcium or ammonium phosphates. Potassium

is ordinarily in the form of potassium chloride or sulfate. Conversions from the oxide forms of P

and K to the elemental expression (N-P-K) can be made using the following formulas:

%P = %P2 05 x 0.437 %K=% K 20x 0.826

2.29 %K 0 = %K x 1.21 %P2 0 5 =%P x 2

In addition to the primary nutrients that are made available to plants via fertilizer added

to soil, secondary nutrients and micronutrients are also essential for plant growth. These are

required in much smaller amounts than those of the primary nutrients. Secondary nutrients

include sulfur (S), calcium (Ca), and magnesium (Mg). Micronutrients include, but are not

limited to, for example, boron (B), zinc (Zn), manganese (Mn), nickel (Ni), molybdenum (Mo),

copper (Cu), iron (Fe), and chlorine (Cl).

Among the micronutrients, boron deficiency is a major concern in many agricultural

areas particularly in sandy soils. Fertilization with boron presents a challenge due to the narrow

window between nutrient deficiency and toxicity. The amount of boron available to a plant's root

zone should be carefully considered as plants are highly sensitive to boron and need only very

small amounts. The presence of high levels of boron can pose risks of seedling injury from

boron toxicity. Traditional methods of bulk blending boron with fertilizer granules, such as

borax, are ineffective or unsuitable due to uneven boron distribution, which can result in too high

levels of B close to the granule and deficient levels further away.

To aid in even distribution of boron, the applicant of the present application proposes that

different sources of boron added to muriate of potash (MOP) granules before or during

compaction, as described in U.S. Patent No. 9,266,784, reduces the occurrence of boron toxicity

and provides an even application of small amounts of boron required by the plant.

Another challenge with respect to boron fertilizer management is providing sufficient

boron during all plant growth stages, as this micronutrient plays crucial roles from seedling to

flowering. Commonly used sources of soluble boron, such as sodium tetraborate, are highly

water soluble and therefore tend to have extremely high mobility in soils compared to most other

nutrients, which the exception of nitrate and sulfate, as it is predominately uncharged in most

soils. Soluble boron sources can therefore be easily leached from soils before being taken up by

the roots, particularly in rainy environments, resulting in boron deficiency later in the growing

season, particularly at flowering. It is therefore a difficult balance of providing an appropriate

level of boron to ensure the plant is getting the essential nutrient during the growing season while

minimizing the occurrence of boron toxicity.

There remains a need for a boron fertilizer product with both fast and slow release

characteristics to ensure even and sufficient distribution of boron to the root zone of plants, while

reducing the risk of boron toxicity.

SUMMARY OF THE INVENTION

Embodiments of the disclosure include a NPK fertilizer product having at least two

sources of boron having different release rates or characteristics. In embodiments, the NPK

fertilizer product can comprise a macronutrient carrier including a nitrogen based fertilizer (e.g.

urea), a potassium based fertilizer (e.g. potash or muriate of potash (MOP)), or a phosphate 3 19153074_1 (GHMatters) P45614AU00 based fertilizer (e.g. mono or di-ammonium phosphate (MAP or DAP)). In one embodiment, a first source of boron is highly soluble, and is therefore a fast release source of boron available to plants in the early stages of the growing season. A second source of boron has lower solubility than the first source, and is therefore a slow release source of boron relative to the first source and is available to plants in the later stages of the growing season. The two sources of boron ensure a more even and continual release of boron than a single source, resulting in increased availability to the root zone of a plant over the course of a growing season, while reducing or eliminating the risk of boron toxicity and seedling injury.

The first source of boron can comprise a highly soluble source or fast release source, such

as, for example, a sodium-based or acidic boron source including sodium tetraborate (i.e. borax)

and/or boric acid, while the second source of boron can comprise a source having a solubility

significantly less than the first source, such as, for example, a calcium-based boron source

including colemanite (CaB304(OH)3.(H20)), and/or boron phosphate (BPO4). For P fertilizers, a

preferred source of slow release boron is boron phosphate. Specifically with respect to boron

phosphate, in embodiments, the solubility can be tailored by heating the reaction product of

phosphoric acid and boric acid to different temperatures. Another source of boron having a

solubility less than the first source and greater than the second source can include, for example,

ulexite (NaCaB5O(OH)6.5(H20)), and can be used as a fast release source when combined with

slower release boron sources, or a slow release source when combined with faster release boron

sources.

In one aspect, there is provided a granular fertilizer composition comprising granules

formed from a compacted muriate of postash composition, the granular fertilizer composition

comprising: muriate of potash containing from about 48.0 weight percent to about 62.0 weight

4 19153074_1 (GHMatters) P45614AU00 percent K20; a first source of boron having a first solubility, wherein the first source of boron is sodium tetraborate; and a second source of boron having a second solubility lower than the first solubility, wherein the second source of boron is colemanite, wherein the first source of boron is configured to be released from the granules at a faster rate than the second source of boron.

The fertilizer product can optionally contain one or more additional sources of

micronutrients and/or secondary nutrients, such as, but not limited to, micronutrients including

an additional source of boron (B), zinc (Zn), manganese (Mn), molybdenum (Mo), nickel (Ni),

copper (Cu), iron (Fe), and/or chlorine (Cl), and/or secondary nutrients including sources of

sulfur (S) in its elemental form, sulfur in its oxidized sulfate form (SO 4 ), magnesium (Mg),

and/or calcium (Ca), or any of a variety of combinations thereof at various concentrations. The

fertilizer can also include a compaction aid, coloring agent, and/or one or more binding

ingredients such as sodium hexametaphosphate (SHMP) in the case of a compacted material.

According to one embodiment of the disclosure in which the carrier comprises a cohered

MOP fertilizer, the fertilizer product is prepared by compacting MOP feed material with at least

two sources of boron. In another embodiment of the disclosure, the fertilizer comprises a

granulated or prilled nitrogen or phosphate-containing carrier formed by standard granulation

processes in which the sources of boron are added within the granulation or prilling circuit.

In another aspect, there is provided a method of forming a fertilizer product containing

multiple sources of boron, the method comprising: providing a fertilizer composition containing

a primary nutrient source comprising muriate of potash containing from about 48.0 weight

percent to about 62.0 weight percent K20, a first source of boron having a first solubility, and a

second source of boron having a second solubility less than the first source, wherein the first

source of boron is sodium tetraborate and the second source of boron is colemanite; compacting

5 19153074_1 (GHMatters) P45614AU00 the fertilizer composition; and crushing the compacted fertilizer composition into fertilizer granules, wherein the first source of boron is configured to be released from the fertilizer granules at a rate faster than the second source of boron.

The above summary of the invention is not intended to describe each illustrated

embodiment or every implementation of the present invention. The detailed description that

follows more particularly exemplifies these embodiments.

5a

19153074_1 (GH Matters) P45614AUD0

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter hereof may be more completely understood in consideration of the

following detailed description of various embodiments in connection with the accompanying

figures, in which:

FIG. 1 depicts a perfusion cell assembly for analyzing leached boron from soil according

to an embodiment of the invention;

FIG. 2 is a plot of a weight percent of boron released as a function of pore volume (i.e. a

time series of boron leaching) for various formulations in a perfusion cell assembly according to

an embodiment of the invention;

FIG. 3 is a pot trial assembly for analyzing boron availability according to an

embodiment of the invention;

FIG. 4 is a plot comparing boron uptake per pot in leached treatments and boron leached

as a percent of added boron versus water-soluble boron as a percent of total boron in a pot trial

assembly;

FIG. 5 is a plot comparing boron uptake per pot per formulation in a pot trial assembly;

FIG. 6 is a graph depicting boron uptake per pot in leached or unleached pots for six

fertilizer treatments in a pot trial assembly;

FIG. 7 is a side by side comparison of canola plants grown in pre-leached pots versus

plants grown in non-leached pots for different formulations in a pot trial assembly according to

an embodiment; and

FIG. 8 is a process flow diagram for a compaction circuit according to an embodiment.

While the invention is amenable to various modifications and alternative forms, specifics

thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION

Embodiments of the invention include a NPK fertilizer product having at least two

sources of boron having different release rates or characteristics to tailor boron availability

during the entire growing season of a plant, while reducing the risk of boron toxicity.

In embodiments, the NPK fertilizer product can comprise a macronutrient carrier

including a nitrogen based fertilizer (e.g. urea), a potassium based fertilizer (e.g. potash or

muriate of potash (MOP)), or a phosphate based fertilizer (e.g. mono or di-ammonium phosphate

(MAP or DAP)). With respect to MOP carriers, the MOP fertilizer base can be any of a variety

of commercially available MOP sources, such as, but not limited to, for example, a MOP feed

material having a K 20content ranging from about 20 weight percent to about 80 weight percent,

more particularly about 48 to 62 weight percent, and more particularly about 55 to 62 weight

percent.

In one embodiment, a first source of boron is highly soluble, and is therefore a fast

release source of boron. A second source of boron has lower solubility than the first source, and

is therefore a slow release source of boron. The first source of boron can comprise a highly

soluble source or fast release source, such as, for example, a sodium-based boron source

including sodium tetraborate (i.e. borax), while the second source of boron can comprise a

source having a solubility significantly less than the first source, such as, for example, a calcium

based boron source including colemanite (CaB 30 4 (OH) 3.(H 2 0)), and/or boron phosphate (BPO 4 ).

Regarding boron phosphate specifically, in embodiments, the solubility can be tailored by

heating the reaction product of phosphoric acid and boric acid to different temperatures and for

different periods of time at a temperature.

Another source of boron having a solubility less than the first source and greater than the

second source can include, for example, ulexite (NaCaB5 O 6(OH).5(H 20)), and can be used as a

fast release source when combined with slower release boron sources, or a slow release source

when combined with faster release boron sources. Table 1 shows the solubility of selected borate

compounds.

Table 1. Solubility of the different sources of boron:

Boron Sources Solubility (mg/L) Sodium borate (borax) 1504 Ulexite 886 Colemanite 538 BPO4 500°C1h 285 BPO4 500 °C 24 h 225 BPO4 800°C1h 75 BPO4 800°C24h 59

In embodiments, at least two sources of boron are present in an amounts which deliver B

from about 0.001 weight percent (wt%) to about 1.0 wt% B in the fertilizer granule, more

particularly from about 0.1 wt% to about 0.7 wt%, and more particularly from about 0.3 wt% to

about 0.6 wt%. Ratios of fast release boron to slow release boron can be, for example, 5:1, 4:1,

3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5, or any of a variety of ratios tailored to the plant needs.

The fertilizer product, in the case of a cohered, compacted granule, can also include one

or more binding agents or ingredients in order to improve the strength or handling ability of the

finished product so that the granules are less likely to wear or break down during handling or

transport, as described in U.S. Patent No. 7,727,501, entitled "Compacted granular potassium chloride, and method and apparatus for production of same," incorporated herein by reference in its entirety. A binding agent is a chemical that is added into the feed of a compaction circuit to improve the strength and quality of compacted particles. The binding agent acts to sequester or chelate impurities in the fertilizer feedstock, while providing adhesive properties to the compacted blend. Binding agents can include, for example, sodium hexametaphosphate (SHMP), tetra-sodium pyrophosphate (TSPP), tetra-potassium pyrophosphate (TKPP), sodium tri polyphosphate (STPP), di-ammonium phosphate (DAP), mono-ammonium phosphate (MAP), granular mono-ammonium phosphate (GMAP), potassium silicate, sodium silicate, starch, dextran, lignosulfonate, bentonite, montmorillonite, kaolin, or combinations thereof. In addition to or alternatively to the binding agents, some of the micronutrients themselves can act as binding agents to improve particle strength.

According to an embodiment of the invention, a cohered granular the NPK fertilizer

product containing at least two sources of boron is made by blending a first source of boron

having a first solubility and a second source of boron having a second solubility less than the

first source into a primary nutrient feed of a compaction circuit. The sources of boron can be

added to the feed in advance of compaction, and can either be added separately to the feed, or

can be bulk blended prior to their addition to the feed. The compaction of this blended feed

stock and then conventional further processing, such as crushing and sizing, yields cohered

fertilizer granules containing at least two sources of boron that are evenly distributed throughout

the granular product.

A production line or production circuit for producing the compacted granular fertilizer

composition generally includes a material feed apparatus such as a belt conveyor, pneumatic

conveyor or the like which input various particulate primary nutrient streams, screenings, recovered or discarded material, the first and second sources of boron, one or more optional secondary nutrients and/or micronutrients, and one or more optional binding agents to a compactor. The compactor then presses the feed material at elevated pressures into a cohered intermediate sheet or cake, which can then be crushed, classified, resized, or otherwise refinished into a desired finished granular product containing the at least two sources of boron.

FIG. 8 is a flow chart illustrating the steps involved in one contemplated embodiment of

the method of production of the present invention. Specifically, FIG. 8 shows the injection of a

boron sources, either blended or separately, into the primary nutrient feed of a production circuit.

The boron sources can be added to the feed material at various locations in the circuit by one or

more injectors including metering equipment to allow more precise control of the amounts of

each component added per unit of feedstock.

After addition of the boron sources and optional binding agent(s) to the feed material, the

additives and feed material are blended. The blending step can either take place passively, by

allowing these materials to come together or blend during their joint carriage through the feed

mechanism, or alternatively there may be specific blending equipment added to the production

circuit between the injector and the compactor to provide more aggressive or active blending of

the boron sources, optional binders, optional other additives, and feedstock prior to compaction.

The blended feed material, now properly mixed with the boron sources and optional other

additives, is then compacted. The compaction process can be performed using conventional

compaction equipment such as a roll compactor or the like. The cohered intermediate

composition yielded can then be further processed into the desired finished granular product

using methods such as crushing, screening or other conventional classification methods suitable

to yield a finished product of the desired particle size or type, as depicted in FIG. 8.

It will be understood that any attendant process or equipment modifications to permit the

addition of one or more additional micronutrients, secondary nutrients, and/or binding agents,

either concurrently or separately, to the feedstock are contemplated within the scope of the

present invention.

The following examples further exemplify embodiments of the present application.

Examples

Trial 1: Column Dissolution

MOP fines were compacted with varying proportions of boron from borax and

colemanite, to give a total boron content of about 0.5 wto of the fertilizer granule. The varying

proportions of boron supplied as borax to colemanite were 1:0 (i.e. no colemanite), 1:1, 1:3, and

0:1 (i.e. no borax). Dissolution of boron from the granules was measured over 72 hours using a

column perfusion technique. Referring to Fig. 1, the column perfusion technique uses a perfusion

cell assembly 100 in which a known weight of fertilizer 102 is embedded within a volume of soil

104 in a vertical column cell 106. A percolation solution S is pumped from bottom to top through

a glass wool barrier 108 followed by the soil 104 which encloses the fertilizer sample 102 and a

portion of acid washed sand 104a. The top end 103 includes a filter paper 110 so that soil is not

removed with the collected leachates 112.

In this particular perfusion example, a one-gram sample of fertilizer product was

embedded within the column of soil. The percolation solution was 10 mM CaCl2 , having a pH of

about 6, and was introduced into the column at a flow rate of 10 mL/h.

The results of the perfusion technique are depicted in the graph of Fig. 2, in which the

weight percent of boron released (i.e. captured in the leachates) per composition was plotted, showing that the fast and slow release characteristics can be tailored by varying the proportions of borax to colemanite.

Trial 2: Pot trials

Pot trials were performed using canola plants, a MOP fertilizer control (without boron),

and the same four fertilizer formulations as used in Trial 1, consisting of MOP with 0.5% boron

and varying ratio of fast (borax) to slow release boron (colemanite) (Table 2). The soil consisted

of 1 kg per pot of Mt. Compass sandy loam, the chemical analysis of which is set forth in Table 3

below. The boron source was added at an equivalent rate of 1.5 kg boron/hectare, which

corresponded to 0.9 mg boron and 86.6 mg K per 1-kg pot. There were five replicates for each

fertilizer treatment.

Table 2: Comparison of acid extrable and water extractable B

MOP4+Borax 100 45.1 0.57 0.52 9. MOP +Colemanite 100 46.1 0.53 O.06 10.8 MOP-+ Colemanite :Bo)rax 50 :50 48. 06 0.29 49.0 MOP + Comanite :Borax 75 25 48.5 0.61 0.8 8. MOP +Ulexite 100 47.0 O.43 0.28 65,1 MOP + Uexite :Borax 5:50 46,5 0,59 0,29 49.

Table 3. Selected characteristics of the Southern Australia soil used in the experiments

Soils Sand Location Mt Compass pH (water) 5.9 pH (CaCl 2 ) 4.9 Total C (%) 0.5 CEC (cmole kg~ ) 2.0 Hot water extractable B(mg kg~ ) 0.20 CaCO 3 (%) <0.2 Clay (%) 4.3 Silt (%) 0.9 Sand (%) 96.3 Field capacity (%) 3.5

In this trial, thirty of the pots were leached, and thirty pots were not leached prior to

planting the canola crop. Referring to Fig. 3, the leached pots 300 were leached by applying four

pore volumes 302 (or 350 mL x4) ofdemineralized water to the 1kg ofsoil 304 to which the

[0 MOP fertilizer 306 was applied at 1cm below the surface of the soil 304. The leachate 308

captured at the bottom of the pot 300 was analyzed for boron. The amount of boron leached from

the pots 300 decreased with increasing amount of slow-release boron in the fertilizer (Fig. 4).

The canola plant crop was then planted and allowed to grow for about twelve weeks, and was then analyzed for boron concentration in the plant shoots. As depicted in Fig. 7, the non-leached pots 700 at varying formulations outgrew the leached pots 702 at the same formulations

As shown in Table 2, and Figs. 2 (column perfusion), 4 (pot trial), 5 (pot trial) and 6 (pot

trial), in both the column perfusion and pot trial techniques, it was observed that as the

percentage of water soluble boron increases, the release rate of boron increases and boron uptake

by plants decreases, while having minimum effect on acid extractable K.

Referring specifically to Fig. 6, the plant uptake of boron per pot was measured after

twelve weeks. In the unleached pots, there was no consistent effect of boron fertilizer

formulation on the uptake of boron. For the leached pots, the plant uptake of boron increased as

the amount of slow-releasing boron from colemanite increased in the fertilizer formulation.

From these trials, it has been determined boron uptake can be improved with the balance

of slow release boron and fast release boron, and that the addition of a slow release source of

boron to a macronutrient fertilizer provides an excellent supply of boron in leaching

environments over the course of a plant's growing season.

Various embodiments of systems, devices, and methods have been described herein.

These embodiments are given only by way of example and are not intended to limit the scope of

the claimed inventions. It should be appreciated, moreover, that the various features of the

embodiments that have been described may be combined in various ways to produce numerous

additional embodiments. Moreover, while various materials, dimensions, shapes, configurations

and locations, etc. have been described for use with disclosed embodiments, others besides those

disclosed may be utilized without exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof

may comprise fewer features than illustrated in any individual embodiment described above.

The embodiments described herein are not meant to be an exhaustive presentation of the ways in

which the various features of the subject matter hereof may be combined. Accordingly, the

embodiments are not mutually exclusive combinations of features; rather, the various

embodiments can comprise a combination of different individual features selected from different

individual embodiments, as understood by persons of ordinary skill in the art. Moreover,

elements described with respect to one embodiment can be implemented in other embodiments

even when not described in such embodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specific combination with one or

more other claims, other embodiments can also include a combination of the dependent claim

with the subject matter of each other dependent claim or a combination of one or more features

with other dependent or independent claims. Such combinations are proposed herein unless it is

stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such that no subject matter

is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference

of documents above is further limited such that no claims included in the documents are

incorporated by reference herein. Any incorporation by reference of documents above is yet

further limited such that any definitions provided in the documents are not incorporated by

reference herein unless expressly included herein.

For purposes of interpreting the claims, it is expressly intended that the provisions of 35

U.S.C. § 112(f) are not to be invoked unless the specific terms "means for" or "step for" are

recited in a claim.

It is to be understood that, if any prior art publication is referred to herein, such reference

does not constitute an admission that the publication forms a part of the common general

knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except

where the context requires otherwise due to express language or necessary implication, the word

"comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e.

to specify the presence of the stated features but not to preclude the presence or addition of

further features in various embodiments of the invention.

16 19153074_1 (GHMatters) P45614AU00

Claims

CLAIMS What is claimed is:

1. A granular fertilizer composition comprising granules formed from a compacted muriate

of postash composition, the granular fertilizer composition comprising:

muriate of potash containing from about 48.0 weight percent to about 62.0 weight percent

K20;

a first source of boron having a first solubility, wherein the first source of boron is

sodium tetraborate; and

a second source of boron having a second solubility lower than the first solubility,

wherein the second source of boron is colemanite,

wherein the first source of boron is configured to be released from the granules at a faster

rate than the second source of boron.

2. The granular fertilizer composition of claim 1, wherein the first and second sources of

boron are present in an amount in the fertilizer granule to provide a total amount of from about

0.001 weight percent (wt%) to about 1.0 wt% B.

3. The granular fertilizer composition of claim 1 or 2, wherein the first and second sources

of boron are present in a total amount of from about 0.1 wt% to about 0.7 wt% B.

4. The granular fertilizer composition of any one of claims 1 to 3, wherein the first and

second sources of boron are present in a total amount of from about 0.3 wt% to about 0.6 wt% B.

17 19153074_1 (GHMatters) P45614AU00

5. The granular fertilizer composition of any one of claims 1 to 4, wherein a ratio of the first

source of boron to the second source of boron is selected from: 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3,

1:4, or 1:5.

6. A method of forming a fertilizer product containing multiple sources of boron, the

method comprising:

providing a fertilizer composition containing a primary nutrient source comprising

muriate of potash containing from about 48.0 weight percent to about 62.0 weight percent K20, a

first source of boron having a first solubility, and a second source of boron having a second

solubility less than the first source, wherein the first source of boron is sodium tetraborate and

the second source of boron is colemanite;

compacting the fertilizer composition; and

crushing the compacted fertilizer composition into fertilizer granules,

wherein the first source of boron is configured to be released from the fertilizer granules

at a rate faster than the second source of boron.

7. The method of claim 6, wherein the first and second sources of boron are present in an

amount in the fertilizer granule to provide a total amount of from about 0.001 weight percent

(wt%) to about 1.0 wt% B.

8. The method of claim 6 or 7, wherein the first and second sources of boron are present in a

total amount of from about 0.1 wt% to about 0.7 wt% B.

18 19153074_1 (GHMatters) P45614AU00

9. The method of any one of claims 6 to 8, wherein the first and second sources of boron are

present in a total amount of from about 0.3 wt% to about 0.6 wt% B.

10. The method of any one of claims 6 to 9, wherein a ratio of the first source of boron to the

second source of boron is selected from: 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5.

11. The method of any one of claims 6 to 10, further comprising:

classifying the fertilizer granules by size.

12. The method of any one of claims 6 to 11, further comprising:

providing a micronutrient other than boron, wherein the at least one micronutrient is

selected from the group consisting of zinc (Zn), manganese (Mn), molybdenum (Mo), nickel

(Ni), copper (Cu), sulfur (S) in its elemental form, sulfur in its oxidized sulfate form(SO 4), and

combinations thereof.

13. The method of any one of claim 6 to 12, wherein each of the sources of boron are

blended together before their addition into the primary nutrient source and compaction.

14. The method of any one of claim 6 to 13, wherein each of the first and second sources of

boron are added separately to the primary nutrient source before compaction.

15. The method of any one of claim 6 to 14, further comprising adding a binding agent

before compaction.

19 19153074_1 (GHMatters) P45614AU00

16. The method of claim 15, wherein the binding agent is selected from the group consisting

of sodium hexametaphosphate (SHMP), tetra-sodium pyrophosphate (TSPP), tetra-potassium

pyrophosphate (TKPP), sodium tri-polyphosphate (STPP); di-ammonium phosphate (DAP),

mono-ammonium phosphate (MAP), granular mono-ammonium phosphate (GMAP), potassium

silicate, sodium silicate, starch, dextran, lignosulfonate, bentonite, montmorillonite, kaolin, or

combinations thereof.

20 19153074_1 (GHMatters) P45614AU00